U.S. patent application number 13/513850 was filed with the patent office on 2012-10-04 for iridium complex and organic light-emitting element including the same.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. Invention is credited to Shigemoto Abe, Masashi Hashimoto, Chiaki Nishiura, Hiroya Nitta.
Application Number | 20120248427 13/513850 |
Document ID | / |
Family ID | 44145536 |
Filed Date | 2012-10-04 |
United States Patent
Application |
20120248427 |
Kind Code |
A1 |
Nishiura; Chiaki ; et
al. |
October 4, 2012 |
IRIDIUM COMPLEX AND ORGANIC LIGHT-EMITTING ELEMENT INCLUDING THE
SAME
Abstract
The present invention provides a novel iridium complex and an
organic light-emitting element including the same. The novel
iridium complex includes phenylpyrazole as a ligand and has a basic
skeleton in which a pyrimidine ring is bonded to a phenyl ring.
Inventors: |
Nishiura; Chiaki;
(Kawasaki-shi, JP) ; Abe; Shigemoto;
(Yokohama-shi, JP) ; Hashimoto; Masashi; (Tokyo,
JP) ; Nitta; Hiroya; (Yokohama-shi, JP) |
Assignee: |
CANON KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
44145536 |
Appl. No.: |
13/513850 |
Filed: |
November 26, 2010 |
PCT Filed: |
November 26, 2010 |
PCT NO: |
PCT/JP2010/071755 |
371 Date: |
June 4, 2012 |
Current U.S.
Class: |
257/40 ;
257/E27.119; 257/E51.026; 544/225 |
Current CPC
Class: |
C07F 15/0033 20130101;
C09K 2211/185 20130101; H01L 51/001 20130101; H01L 51/0085
20130101; C09K 11/06 20130101; C09K 2211/1007 20130101; H01L
51/5016 20130101; H05B 33/14 20130101; C09K 2211/1044 20130101;
Y10S 428/917 20130101 |
Class at
Publication: |
257/40 ; 544/225;
257/E51.026; 257/E27.119 |
International
Class: |
H01L 27/32 20060101
H01L027/32; C07F 15/00 20060101 C07F015/00; H01L 51/54 20060101
H01L051/54 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 8, 2009 |
JP |
2009-278969 |
Claims
1. An iridium complex represented by the following general formula
(1): ##STR00028## wherein R.sub.1 and R.sub.2 are each
independently selected from a tertiary butyl group, an adamantyl
group, and a bicyclooctyl group, R.sub.3 is selected from a
hydrogen atom, a halogen atom, and a cyano group, R.sub.4 and
R.sub.5 are each independently selected from a hydrogen atom, a
halogen atom, a cyano group, an alkyl group, an alkoxy group, and
an amino group, and R.sub.6 is an alkyl group.
2. The iridium complex according to claim 1, wherein both the
R.sub.1 and R.sub.2 are tertiary butyl groups.
3. The iridium complex according to claim 1, wherein the R.sub.6 is
a methyl group.
4. The iridium complex according to claim 1, wherein blue light is
emitted.
5. A material for an organic light-emitting element comprising the
iridium complex according to claim 1.
6. An organic light-emitting element comprising a pair of
electrodes and an organic compound layer disposed between the pair
of electrodes, wherein the organic compound layer contains the
iridium complex according to claim 1.
7. The organic light-emitting element according to claim 6, wherein
the organic compound layer is a light-emitting layer, the
light-emitting layer includes a host material and a guest material,
and the guest material contains the iridium complex.
8. A display device comprising a plurality of pixels, each of the
pixels including the organic light-emitting element according to
claim 6 and a switching element connected to the organic
light-emitting element.
Description
TECHNICAL FIELD
[0001] The present invention relates to a novel iridium complex and
an organic light-emitting element including the same.
BACKGROUND ART
[0002] Organic light-emitting elements are being actively
developed. Novel phosphorescent materials are being developed for
developing organic light-emitting elements. Patent Literature 1
describes an iridium complex represented by the following
structural formula.
##STR00001##
CITATION LIST
[0003] Patent Literature
[0004] [PTL 1] Japanese Patent Laid-Open No. 2005-053912
[0005] Although the structural formula described in Patent
Literature 1 is disclosed, light emission characteristics are not
specifically described. In addition, compounds of the above
structural formual have a weak lgand field and cannot be expected
to have excellent light emission characteristics as blue
light-emitting materials.
[0006] The present invention provides an iridium complex which
emits blue phosphorescence and has excellent light emission
characteristics. Also the present invention provides an organic
light-emitting element including the iridium complex and having
excellent external quantum yield.
SUMMARY OF INVENTION
[0007] The present invention provides an iridium complex
represented by the following general formula (1):
##STR00002##
[0008] In the formula (1), R.sub.1 and R.sub.2 are each
independently selected from a tertiary butyl group, an adamantyl
group, and a bicyclooctyl group. R.sub.3 is any one of a hydrogen
atom, a halogen atom, and a cyano group. R.sub.4 and R.sub.5 are
each independently selected from a hydrogen atom, a halogen atom, a
cyano group, an alkyl group, an alkoxy group, and an amino group.
R.sub.6 is an alkyl group.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a diagram showing an emission spectrum of compound
1-1 according to the present invention.
[0010] FIG. 2 is a diagram showing an emission spectrum of compound
9 of a comparative example.
[0011] FIG. 3 is a schematic sectional view showing an organic
light-emitting element and a switching element connected to the
organic light-emitting element.
DESCRIPTION OF EMBODIMENTS
[0012] An iridium complex according to the present invention is
represented by the following general formula (1):
##STR00003##
[0013] R.sub.1 and R.sub.2 are each independently selected from a
tertiary butyl group, an adamantyl group, and a bicyclooctyl group.
R.sub.3 is any one of a hydrogen atom, a halogen atom, and a cyano
group. R.sub.4 and R.sub.5 are each independently selected from a
hydrogen atom, a halogen atom, a cyano group, an alkyl group, an
alkoxy group, and an amino group. R.sub.6 is an alkyl group.
[0014] A halogen atom as R.sub.3 is, for example, a fluorine atom,
a chlorine atom, a bromine atom, or an iodine atom. Substituents
R.sub.4 and R.sub.5 may be the same or different from each other. A
halogen atom as each of R.sub.4 and R.sub.5 is, for example, a
fluorine atom, a chlorine atom, a bromine atom, or a iodine atom.
An alkyl group as each of R.sub.4 and R.sub.5 is, for example, a
methyl group, an ethyl group, an isopropyl group, a tertiary butyl
group, or a adamantyl group. An amino group as each of R.sub.4 and
R.sub.5 is, for example, a dimethylamino group or a
diisopropylamino group. An alkyl group as R.sub.6 is, for example,
a methyl group, an ethyl group, an isopropyl group, a tertiary
butyl group, or an adamantyl group.
[0015] As shown in the general formula (1), an iridium complex
represented by the general formula (1) according to the present
invention has a ligand with a skeleton in which a pyrimidine ring,
a phenyl ring, and a pyrazole ring, excluding R.sub.1 to R.sub.6
and H, are bonded at specified positions. This skeleton is referred
to as a "ligand main skeleton of general formula (1)"
hereinafter.
[0016] Blue phosphorescence emission of the iridium complex of the
present invention is exhibited by virtue of the ligand main
skeleton of general formula (1).
[0017] Conceivable ligand structures including a pyrimidine ring, a
phenyl ring, and a pyrazole ring include four structures A to D
described below. However, the structure C, i.e., the ligand main
skeleton of general formula (1), is excellent as a basic skeleton
of light-emitting materials in a blue region.
##STR00004##
[0018] In order to achieve excellent light emission characteristics
in the blue region, it is necessary to use a ligand capable of
forming a strong ligand field.
[0019] In order to increase the ligand field, it is important to
increase .PI. back donation from iridium as a central metal to the
ligand.
[0020] The term ".PI. back donation" represents that electrons are
donated from a central metal to a ligand in a complex.
[0021] The inventors have found that two requirements below are
important for effectively producing the .PI. back donation due to
the electron-withdrawing property of a pyrimidine ring. The
structures A to D have iridium, a pyrimidine ring, a phenyl ring,
and a pyrazole ring.
[0022] Requirement 1: A substitution position of a pyrimidine ring
bonded to a phenyl ring bonded to iridium is the ortho or para
position on the phenyl ring with respect to iridium.
[0023] Requirement 2: A pyrimidine ring and a phenyl ring are
coplanar to each other.
[0024] Structure B contains a pyrimidine ring at the metha position
on a phenyl ring with respect to iridium and does not satisfy
requirement 1.
[0025] Structures A and D each contain a phenyl ring and a
pyrimidine ring which cannot maintain a planar structure in three
dimensions due to steric repulsion, at an adjacent position to a
bonding position of a pyrimidine ring, of iridium atom in structure
A and of a pyrazole ring in structure D. Therefore, structures A
and D do not satisfy requirement 2.
[0026] Therefore, only structure C satisfies the two requirements
and is excellent as a light-emitting material in the blue region,
which has the ligand main skeleton of general formula (1).
[0027] Further, two H atoms possessed by a phenyl ring, i.e., two H
atoms represented by the general formula (1), are important for
maintaining planarity of a pyrimidine ring and a phenyl ring.
[0028] The values of dihedral angle between a pyrimidine ring and a
phenyl ring determined by molecular orbital calculation are shown
in a table below.
TABLE-US-00001 [Chem. 5] Struc- tural for- mula ##STR00005##
##STR00006## ##STR00007## Dihe- dral angle be- tween two rings
0.00.degree. 47.9.degree. 54.4.degree.
[0029] Therefore, from the viewpoint of maintaining planarity of a
pyrimidine ring and a phenyl ring, it is important that two ortho
positions on a phenyl ring with respect to a pyrimidine ring are
hydrogen atoms.
[0030] A dihedral angle was calculated using a commercial software
for electronic state calculation, Gaussian 03* Revision D.01.
Geometry optimization calculation was performed, using the
software, for a ground state of a phenyl group with fluorine and a
methyl group introduced at the 2 and 6 positions.
[0031] In this case, density functional theory was used as a
quantum chemical calculation method, and B3LYP was used as a
functional. In Gaussian 30, Revision D.01, 6-31G* was used as a
basis function.
* Gaussian 03, Revision D.01,
M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, J. A. Montgomery, Jr., T. Vreven,
K. N. Kudin, J. C. Burant, J. M. Millam, S. S. Iyengar, J.
Tomasi,
V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega,
G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota,
R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O.
Kitao,
H. Nakai, M. Klene, X. Li, J. E. Knox, H. P. Hratchian, J. B.
Cross,
V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E.
Stratmann,
O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski,
P. Y. Ayala, K. Morokuma, G. A. Voth, P. Salvador, J. J.
Dannenberg,
V. G. Zakrzewski, S. Dapprich, A. D. Daniels, M. C. Strain, O.
Farkas, D. K. Malick, A. D. Rabuck, K. Raghavachari,
J. B. Foresman, J. V. Ortiz, Q. Cui, A. G. Baboul, S. Clifford,
J. Cioslowski, B. B. Stefanov, G. Liu, A. Liashenko, P.
Piskorz,
I. Komaromi, R. L. Martin, D. J. Fox, T. Keith, M. A. Al-Laham,
C. Y. Peng, A. Nanayakkara, M. Challacombe, P. M. W. Gill, B.
Johnson, W. Chen, M. W. Wong, C. Gonzalez, and J. A. Pople,
Gaussian, Inc., Wallingford Conn., 2004.
[0032] Although R.sub.1 and R.sub.2 in the general formula (1) are
each independently selected, they are the same substituent from the
viewpoint of simplicity of material synthesis.
[0033] The substituents R.sub.1 and R.sub.2 are provided for
protecting the pyrimidine ring. Therefore, it is important that the
substituents are bulky substituents. Specifically, as described
above, R.sub.1 and R.sub.2 are each any one of a tertiary butyl
group, an adamantyl group, and a bicyclooctyl group. For example, a
tertiary butyl group can be used for avoiding an excessive increase
in molecular weight of the iridium complex.
[0034] By introducing an alkyl group with a large excluded volume,
at least any one of the followings can be expected.
[0035] 1. A high purity and high yield can be achieved.
[0036] 2. Incorporation of ionic impurities due to a lone electron
pair is suppressed by suppressing the coordinative ability of a
nitrogen atom, thereby improving the life of an organic
light-emitting element.
[0037] 3. Concentration quenching of a light-emitting material can
be suppressed by suppressing intermolecular interaction. The
concentration quenching represents a phenomenon that luminous
efficiency is decreased at a high concentration.
[0038] In the general formula (1), R.sub.6 is an alkyl group. This
indicates that R.sub.6 is not a hydrogen atom. When R.sub.6 is a
hydrogen atom, a by-product is undesirably produced due to a
tautomer of hydrogen in synthesis of the complex. In addition, from
the viewpoint of synthesis yield of the complex, a substituent
having a small excluded volume can be used. Specifically, a methyl
group can be used.
[0039] The iridium complex according to the present invention can
be used for a blue phosphorescent material. Therefore, the iridium
complex can be used as a light-emitting material of an organic
light-emitting element. The light-emitting element is described
later. In addition, the iridium complex of the present invention
has a band gap sufficient for use as a host material of a
light-emitting layer of an organic light-emitting element which
emits green or red light.
[0040] Specific examples of the iridium complex according to the
present invention are given below.
##STR00008## ##STR00009## ##STR00010## ##STR00011## ##STR00012##
##STR00013## ##STR00014##
[0041] The iridium complex according to the present invention is
useful as a material for an organic light-emitting element. Also,
the iridium complex according to the present invention can be used
as a guest material or a host material of a light-emitting layer of
an organic light-emitting element. The organic light-emitting
element includes a pair of opposing electrodes and a light-emitting
layer disposed between the electrodes. The organic light-emitting
layer may include a layer other than the light-emitting layer. The
iridium complex according to the present invention can be properly
used for a layer other than the light-emitting layer, i.e., any one
of an electron transport layer, an electron injection layer, a hole
transport layer, a hole injection layer, and an exciton/hole
blocking layer.
[0042] As for the host material and the guest material, herein, the
host material is a compound at the highest weight ratio among the
compounds constituting the light-emitting layer, and the guest
material is a compound at a lower weight ratio than that of the
host material among the compounds constituting the light-emitting
layer.
[0043] The iridium complex according to the present invention can
be used as a guest material of a light-emitting layer of an organic
light-emitting element. In particular, the iridium complex can be
used as a guest material of a blue light-emitting element.
[0044] An emission wavelength can be changed by introducing a
substituent into the basic skeleton of the iridium complex
according to the present invention.
[0045] When the iridium complex according to the present invention
is used as a guest material of a light-emitting layer, a material
having a higher LUMO level than the iridium complex, in other
words, a host material in a level close to the vacuum level, can be
used as a host material. This is because since the iridium complex
according to the present invention has a low LUMO level, electrons
supplied to the light-emitting layer, i.e., the host material, can
be more satisfactorily received from the host material. The LUMO
level is an abbreviation of the lowest unoccupied molecular orbital
level. In addition, a HOMO level is an abbreviation of the highest
occupied molecular orbital level. The host material and the guest
material are further described later.
[0046] Next, synthesis examples of the iridium complex according to
the present invention are described, starting from a synthesis
example of a ligand.
(Description of Synthesis Route)
[0047] First, a synthesis example of a ligand is described.
<Synthesis Example of Ligand>
##STR00015##
[0049] In this scheme, various substituents can be introduced by
changing R.sub.7-MgCl as a Grignard reagent.
##STR00016##
[0050] In this scheme, various ligands can be synthesized using, as
a raw material, halogen materials containing substituents
introduced as R.sub.8 to R.sub.10. In addition, various
substituents can be introduced by changing a halide
R.sub.11--I.
##STR00017##
[0051] In this scheme, a halogen material used as a raw material is
not limited to a bromine material and may be, for example, an
iodide material or triflate. In addition, a product may be boronic
acid or the like.
##STR00018##
[0052] Various ligands can be synthesized by selecting halogenated
pyrimidine synthesized in Scheme 1 and a boronic acid derivative
with 3-phenylpyrazole as a basic skeleton synthesized in Scheme
3.
[0053] Next, synthesis examples of the iridium complex are
described.
<Synthesis Examples of Iridium Complex>
[0054] Here, two examples of synthesis of the iridium complex are
described.
<One-Step Synthesis Example>
[0055] A one-step synthesis example using iridium
trisacetylacetonate complex as a raw material is described.
##STR00019##
[0056] In this scheme, a solvent is not particularly specified, but
a protonic solvent having a high boiling point, such as ethylene
glycol, glycerol, or the like, can be used.
<Three-Step Synthesis Example>
[0057] Next, a three-step synthesis example using iridium
trichloride as a raw material is described.
##STR00020##
[0058] A reaction in the third step in this scheme may be performed
using, for example, ethylene glycol or glycerol, or may be
solvent-less reaction.
[0059] Next, an organic light-emitting element according to the
present invention is described.
[0060] An organic light-emitting element according to the present
invention includes a pair of electrodes and an organic compound
layer disposed between the pair of electrodes. The pair of
electrodes include, for example, an anode and a cathode. An
electric field in a forward direction necessary for emitting light
or an electric field in a reverse direction may be applied to the
pair of electrodes.
[0061] The organic compound layer includes the iridium complex
according to the present invention.
[0062] Other than this organic compound layer, the organic
light-emitting element may contain an organic compound layer.
[0063] The organic light-emitting element according to the present
invention includes a light-emitting layer disposed between the
anode and the cathode. The light-emitting layer may be an organic
compound layer containing the iridium complex according to the
present invention or may include the organic compound layer
containing the iridium complex according to the present invention
and another organic compound layer. The organic compound layer
containing the iridium complex according to the present invention
may be or not be the light-emitting layer. For example, at least
any one of a hole injection layer, a hole transport layer, a
hole/exciton blocking layer, an electron transport layer, and an
electron injection layer may contain the iridium complex according
to the present invention.
[0064] A combination of the organic compound layer containing the
iridium complex according to the present invention and another
organic layer may be appropriately selected. A plurality of other
organic compound layers may be provided.
[0065] A layer structure between the anode and the cathode of the
organic light-emitting element according to an embodiment of the
present invention is described.
[0066] A first layer structure is formed by laminating the anode,
the light-emitting layer, and the cathode.
[0067] A second layer structure includes a laminate of the anode,
the hole transport layer, and the electron transport layer. In this
case, when light emission is observed between the hole transport
layer and the electron transport layer, the light-emitting layer
may include the hole transport layer and the electron transport
layer.
[0068] A third layer structure includes a laminate of the anode,
the hole transport layer, the light-emitting layer, the electron
transport layer, and the cathode.
[0069] A fourth layer structure includes a laminate of the anode,
the hole injection layer, the hole transport layer, the
light-emitting layer, the electron transport layer, and the
cathode.
[0070] A fifth layer structure includes a laminate of the anode,
the hole transport layer, the light-emitting layer, the
hole/exciton blocking layer, the electron transport layer, and the
cathode.
[0071] The iridium complex according to the present invention can
be used for any of the layers in these first to fifth layer
structures.
[0072] An organic compound which constitutes the hole injection
layer or the hole transport layer is a compound having high hole
mobility. In this case, the organic compound may be a low-molecular
compound or a high-molecular compound. Examples of such a compound
include triarylamine derivatives, phenylenediamine derivatives,
stilbene derivatives, phthalocyanine derivatives, polyphyrin
derivatives, poly(vinylcarbazole), poly(thiophene), and other
conductive polymers. Examples are shown below.
##STR00021##
[0073] An organic compound which constitutes the electron injection
layer or the electron transport layer is selected in consideration
of balance with the hole mobility of the compound contained in the
hole injection layer or the hole transport layer. Examples of the
compound include oxadiazole derivatives, oxazole derivatives,
pyrazine derivatives, triazole derivatives, triazine derivatives,
quinoline derivatives, quinoxaline derivatives, phenanthroline
derivatives, organic aluminum complexes, and the like. Examples are
shown below.
##STR00022##
[0074] The light-emitting layer may be composed of only a single
organic compound or a plurality types of organic compounds. When
the light-emitting layer contains a plurality types of organic
compounds, the plurality types of organic compounds include a host
material and the guest material. The host material is a main
component of the light-emitting layer had has a higher weight ratio
than the guest material. The amount of the guest material as a
sub-component is 0.01 wt % or more and 20 wt % or less and more
preferably 0.5 wt % or more and 10 wt % or less of the total weight
of the light-emitting layer. The guest material is a light-emitting
material that determines the luminescent color of the organic
light-emitting element. When the light-emitting layer contains a
plurality types of organic compounds, the plurality types of
organic compounds may include an emission assist material and a
charge injection material besides the host material and the guest
material.
[0075] The host material may be a material in which carriers of
both holes and electrons sufficiently move. In addition, a material
having a higher triplet lowest excitation energy level T1 than that
of the light-emitting material can be used in order that excitons
produced in the light-emitting layer are efficiently utilized for
light emission. Examples of the host material include fused ring
compounds (e.g., fluorene derivatives, naphthalene derivatives,
carbazole derivatives, quinoxaline derivatives, and quinoline
derivatives), organic aluminum complexes such as
tris(8-quinolinolate)aluminum and the like, organic zinc complexes,
and polymer derivatives such as triphenylamine derivatives,
poly(fluorene) derivatives, poly(phenylene) derivatives, and the
like. Examples are shown below.
##STR00023##
[0076] A material having as large work function as possible can be
used for the anode. Examples of such a material include elemental
metals such as gold, platinum, silver, copper, nickel, palladium,
cobalt, selenium, vanadium, tungsten, and the like, alloys thereof,
metal oxides such as tin oxide, zinc oxide, indium oxide, indium
tin oxide (ITO), indium zinc oxide, and the like. Also, conductive
polymers such as polyaniline, polypyrrole, polythiophene, and the
like can be used. These electrode materials may be used alone or in
combination of two or more. In addition, the anode may have a
single layer structure or a multilayer structure.
[0077] A material having small work function can be used for the
cathode. Examples of such a material include elemental metals such
as alkali metals, e.g., lithium and the like, alkaline-earth
metals, e.g., calcium and the like, aluminum, titanium, manganese,
silver, lead, chromium, and the like. Also, alloys of combination
of these elemental metals can be used. For example,
magnesium-silver, aluminum-lithium, aluminum-magnesium, and the
like can be used. Also, metal oxides such as indium tin oxide (ITO)
and the like can be used. These electrode materials may be used
alone or in combination of two or more. In addition, the cathode
may have a single layer structure or a multilayer structure.
[0078] A layer containing the iridium complex according to the
present invention and a layer containing another organic compound
are formed by a method described below. A thin film is formed by a
vacuum evaporation method, an ionized evaporation method,
sputtering, plasma coating, or a coating method of allying a
solution in a proper solvent (for example, spin coating, dipping,
casting, LB method, an ink jet method, or the like). When a layer
is formed by the vacuum evaporation method, the solution coating
method, or the like, crystallization little occurs, and temporal
stability is excellent. When a film is formed by the coating
method, the film can be formed by combining a proper binder
resin.
[0079] Examples of the binder resin are given below. Examples
include a polyvinyl carbazole resin, polycarbonate resin, a
polyester resin, an ABS resin, an acrylic resin, a polyimide resin,
a phenol resin, an epoxy resin, a silicone resin, and a urea
resin.
[0080] These binder resins may be used alone as a homopolymer or a
copolymer or used as a mixture of two or more. Further, if
required, known additives such as a plasticizer, an antioxidant, an
ultraviolet absorber, and the like may be used in combination.
[0081] The organic light-emitting element according to the present
invention can be used in a display device and an illuminating
device. Besides these, the organic light-emitting element can be
used for an exposure light source of an electrophotographic image
forming apparatus, a back light of a liquid crystal display device,
and the like.
[0082] The display device includes the organic light-emitting
element according the present invention provided in a display
portion. The display device is capable of display by virtue of the
organic light-emitting element.
[0083] In addition, the display portion includes a pixel which may
include the organic light-emitting element according to the present
invention. The display device can be used as an image display
device of PC or the like.
[0084] The display device can also be used in a display portion of
an imaging apparatus such as a digital camera, a digital video
camera, or the like. The imaging apparatus includes the display
portion and an imaging portion having an imaging optical system for
taking images.
[0085] The display device may include an image input portion and a
display portion. The image input portion serves as the imaging
optical system, a light-receiving unit of CCD or the like, a unit
which receives a memory card or the like, a scanner, or the like.
Besides the above-described digital camera and digital video
camera, the apparatus including the organic light-emitting element
according to the present invention provided in the display portion
may be, for example, a multifunction-type image forming apparatus
having a scanner function and an image output function. The
multifunction-type image forming apparatus may be an ink jet image
forming apparatus or an electrophotographic image forming
apparatus.
[0086] Next, a display device using the organic light-emitting
element according to the present invention is described.
[0087] FIG. 3 is a schematic sectional view of a display device
which shows an organic light-emitting element serving as a pixel
and a switching element connected to the organic light-emitting
element. In this figure, the switching element is a TFT element.
Other than this, the switching element may be a MIM element.
[0088] A display device 3 includes a substrate 31 of glass or the
like and a moisture proofing film 32 provided thereon to protect a
TFT element or an organic compound layer. In addition, reference
numeral 33 denotes a gate electrode of a metal such as Cr or the
lie. Reference numeral 34 denotes a gate insulting film, and
reference numeral 35 denotes a semiconductor layer.
[0089] A TFT element 38 includes the semiconductor film 35, a drain
electrode 36, and a source electrode 37. An insulating film 39 is
provided over the TFT element 38. An anode 311 of the organic
light-emitting element is connected to the source electrode 37
through a contact hole (through hole) 310.
[0090] In FIG. 3, a plurality of organic compound layers 312 is
shown as a single layer for the sake of convenience. Further, a
first protective layer 314 and a second protective layer 315 are
provided on a cathode 313 in order to suppress deterioration of the
organic light-emitting element.
[0091] The emission luminance of the organic light-emitting element
is controlled by the TFT element. A plurality of organic
light-emitting elements are provided in a plane so that an image
can be displayed with emission luminance of each of the
elements.
EXAMPLES
[0092] Examples are described below.
Example 1
Synthesis of Exemplified Example 1-1
##STR00024##
[0093] Synthesis of Intermediate Compound 2
[0094] In a 500 ml three-necked flask, 20.0 g (109 mmol) of
compound 1, 1.04 g (5.45 mmol) of copper iodide, and 100 ml of THF
were placed, followed by cooling to -20.degree. C. After bubbling
with nitrogen for 10 minutes, 120 ml (241 mmol) of a 2 mol/L
tert-butylmagnesium chloride THF solution was added dropwise at a
rate such that the reaction solution did not exceed 0.degree. C.
After the addition, the solution was stirred at room temperature
for 24 hours. The loss of the raw materials and production of a new
compound were confirmed by gas chromatography. An organic phase was
recovered by three times of separation using a tert-butyl methyl
ether/an aqueous saturated ammonium chloride solution and then
separation with tert-butyl methyl ether/water. The organic phase
was dried over magnesium sulfate, concentrated, and then purified
by silica gel column chromatography (developing solvent;
heptane:toluene=6:1). A target substance was concentrated to
produce 19.5 g (85.6 mmol) of compound 2 (yield 80.0%). One proton
was attributed by .sup.1H-NMR (CDCl.sub.3: 7.20 (s, 1H)). A peak
was observed at m/z=183 in GS-MS (gas chromatography direct-coupled
to mass spectrometry) to confirm the target compound.
Synthesis of Intermediate Compound 4
[0095] In a 300 ml eggplant-type flask, 7.00 g (31.4 mmol) of
compound 3, 3.30 g (34.5 mmol) of sodium tert-butoxide, and 100 ml
of DMF were placed. Then, 2.15 ml (34.5 mmol) of idomethane was
added dropwise to the resultant mixture, followed by stirring at
room temperature for 24 hours. The loss of the raw materials and
production of a new compound were confirmed by TLC (Thin Layer
Chromatography). The reaction solution was concentrated, and an
organic phase was recovered by three times of separation with
toluene/water. The organic phase was dried over magnesium sulfate,
concentrated, and then purified by silica gel column chromatography
(developing solvent toluene:heptane:ethyl acetate=10:10:1). A
target substance was concentrated to produce 5.21 g (22.0 mmol) of
compound 4 (yield 70.0%). Nine protons were attributed by
.sup.1H-NMR (CDCl.sub.3: 7.95 (s, 1H), 7.71 ppm (d, 1H), 7.42-7.39
ppm (m, 2H), 7.26 ppm (t, 1H), 6.53 ppm (d, 1H), 3.96 ppm (s, 3H)).
A peak was observed at m/z=236 in GS-MS (gas chromatography
direct-coupled to mass spectrometry) to confirm the target
compound.
Synthesis of Intermediate Compound 5
[0096] In a 500 ml eggplant-type flask, 5.00 g (21.1 mmol) of
compound 4, 5.89 g (23.2 mmol) of bis(pinacolato)diboron, and 300
ml of dioxane were placed, followed by bubbling with nitrogen for
15 minutes. Then, 296 mg (0.422 mmol) of
bis(triphenylphosphine)palladium(II) dichloride and 6.20 g (63.0
mmol) of potassium acetate were added to the resultant mixture,
followed by stirring under heating at 80.degree. C. for 8 hours.
The loss of the raw materials and production of a new compound were
confirmed by TLC (Thin Layer Chromatography). An organic phase was
recovered by two times of separation with toluene/water. The
organic phase was dried over magnesium sulfate, concentrated, and
then purified by silica gel column chromatography (developing
solvent; toluene:heptane:ethyl acetate=1:4:1). A target substance
was concentrated to produce 4.20 g (14.8 mmol) of compound 5 (yield
75.0%). Twenty seven protons were attributed by .sup.1H-NMR to
confirm the target compound (CDCl.sub.3: 8.19 (s, 1H), 7.94 ppm (d,
1H), 7.74 ppm (d, 1H), 7.40 ppm (t, 1H), 7.37 ppm (d, 1H), 6.60 ppm
(d, 1H), 3.95 ppm (s, 3H), 1.38-1.32 ppm (m, 18H)).
Synthesis of Intermediate Compound 6
[0097] In a 500 ml eggplant-type flask, 2.63 g (11.6 mmol) of
compound 2, 3.00 g (10.6 mmol) of compound 5, 150 ml of toluene, 75
ml of ethanol, and 150 ml of water were placed, followed by
bubbling with nitrogen for 15 minutes. Then, 366 mg (0.317 mmol) of
tetrakis(triphenylphosphine) palladium(0) and 31 g (292 mmol) of
potassium carbonate were added to the resultant mixture, followed
by stirring under heating at 80.degree. C. for 8 hours. The loss of
the raw materials and production of a new compound were confirmed
by TLC (Thin Layer Chromatography). An organic phase was recovered
by two times of separation with toluene/water. The organic phase
was dried over magnesium sulfate, concentrated, and then purified
by silica gel column chromatography (developing solvent;
toluene:heptane:ethyl acetate=1:3:1). A target substance was
concentrated to produce 3.40 g (9.75 mmol) of compound 6 (yield
92.0%). Twenty seven protons were attributed by .sup.1H-NMR to
confirm the target compound (CDCl.sub.3: 8.91 (s, 1H), 8.51 ppm (d,
1H), 7.95 ppm (d, 1H), 7.50 ppm (t, 1H), 7.42 ppm (d, 1H), 7.19 ppm
(s, 1H), 6.67 ppm (d, 1H), 3.96 ppm (s, 3H), 1.40-1.35 ppm (m,
18H)).
##STR00025##
Synthesis of Intermediate Compound 7
[0098] In a 100 ml eggplant-type flask, 1.00 g (2.87 mmol) of
compound 6, 460 mg (1.30 mol) of iridium trichloride trihydrate, 20
ml of 2-ethoxyethanol, and 7 ml of water were placed. After
bubbling with nitrogen for 10 minutes, the resulting mixture was
stirred under heating at 100.degree. C. for 12 hours. Then, a small
amount of sample was collected from the reaction solution and
analyzed by .sup.1H-NMR to confirm the production of a new
compound. After the reaction solution was returned to room
temperature, precipitates were filtered off. The precipitates were
washed with 20 ml of methanol and filtered off to produce 779 mg
(0.422 mmol) of compound 7 (yield 68.0%). One hundred and eight
protons were attributed by .sup.1H-NMR to confirm the target
compound (CDCl.sub.3: 8.42 (s, 4H), 7.73 ppm (d, 4H), 7.58 ppm (d,
4H), 7.00 ppm (s, 4H), 6.82 ppm (d, 4H), 6.02 ppm (d, 4H), 3.84 ppm
(s, 12H), 1.38-1.32 ppm (m, 72H)).
Synthesis of Intermediate Compound 8
[0099] In a 100 ml eggplant-type flask, 500 mg (0.271 mmol) of
compound 7, 271 .mu.l (2.71 mmol) of acetylacetone, 144 mg (1.36
mmol) of sodium carbonate, and 15 ml of 2-ethoxyethanol were
placed. The resultant mixture was stirred under heating at
100.degree. C. for 12 hours. Then, a small amount of sample was
collected from the reaction solution and analyzed by .sup.1H-NMR to
confirm the production of a new compound. After the reaction
solution was returned to room temperature, 30 ml of water was added
to the solution and stirred for 10 minutes, and precipitates were
filtered off. The precipitates were washed with 20 ml of methanol
and filtered off to produce 446 mg (0.452 mmol) of compound 8
(yield 83.0%). Fifty five protons were attributed by .sup.1H-NMR to
confirm the target compound (CDCl.sub.3: 8.46 (s, 2H), 7.81 ppm (d,
2H), 7.49 ppm (d, 2H), 7.00 ppm (s, 2H), 6.72 ppm (d, 2H), 6.24 ppm
(d, 2H), 5.33 ppm (s, 1H), 3.84 ppm (s, 6H), 1.38-1.32 ppm (m,
36H)).
Synthesis of Exemplified Compound 1-1
[0100] In a 10 ml eggplant-type flask, 200 mg (0.203 mmol) of
compound 8 and 1.00 g (2.87 mmol) of compound 6 were placed. The
resultant mixture was stirred under heating at 220.degree. C. for
24 hours. The loss of the raw materials and production of a new
compound were confirmed by TLC. The reaction solution was washed
with 30 ml of toluene and filtered. The filtered residue was
dissolved in DMF and purified by alumina column chromatography
(developing solvent DMF). Further, the product was recrystallized
with DMF to produce 37.5 mg (0.0406 mmol) of exemplified compound
1-1 (yield 20.0%). Eighty one protons were attributed by
.sup.1H-NMR (CDCl.sub.3: 8.56 (s, 3H), 7.94 ppm (dd, 3H), 7.21 ppm
(d, 3H), 7.02 ppm (s, 3H), 6.87 ppm (d, 3H), 6.63 ppm (d, 3H), 3.23
ppm (s, 9H), 1.37-1.32 ppm (m, 54H)). A peak was observed at
m/z=1234 in MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization
Time-Of-Flight Mass Spectrometry) to confirm the target
compound.
[0101] An emission spectrum of the exemplified compound 1-1 was
measured at room temperature. As measurement conditions, a
1.times.10.sup.-5 mol/1 toluene solution was measured using Hitachi
F-4500 at an excitation wavelength of 350 nm. The exemplified
compound 1-1 showed a spectrum having a maximum wavelength of 466
nm at room temperature. The half-width of the emission spectrum was
50 nm, and chromaticity was x=0.14 and y=0.25 in the CIE standard
color system.
[0102] In addition, for comparison, FIG. 2 shows a spectrum, at
room temperature, of compound 9 which was an iridium complex used
as a general blue light-emitting material and represented by the
following structural formula:
##STR00026##
[0103] This compound has a maximum wavelength of 468 nm. The
half-width of the emission spectrum was 66 nm, and chromaticity was
x=0.15 and y=0.34 in the CIE standard color system.
[0104] According to the above-described measurement, the
exemplified compound 1-1 has a half-width value 16 nm narrower than
that of compound 9.
[0105] In addition, the exemplified compound 1-1 has chromaticity
closer to blue (x=0.14 and y=0.08 in the CIE standard color system)
in the NTSC system than the compound 9 and is thus excellent as a
blue light-emitting material for display. Namely, the compound of
the present invention has an emission spectrum having a narrow
half-width and is excellent as a blue light-emitting material.
[0106] A glass substrate on which indium tin oxide (ITO) was
deposited to a thickness of 120 nm by sputtering to form an anode
was used as a transparent conductive support substrate. The
substrate was ultrasonically washed with acetone and isopropyl
alcohol (IPA) in order, washed by boiling in IPA, and then dried.
Further, the substrate was washed with UV/ozone and used as the
transparent conductive support substrate.
[0107] A chloroform solution of a compound represented by compound
10 was deposited to a thickness of 30 nm on the transparent
conductive support substrate by spin coating to form a hole
injection layer.
[0108] Further, organic layers and electrode layers described below
were continuously formed by resistance-heating vacuum evaporation
in a vacuum chamber of 10.sup.-5 Pa to produce an element.
[0109] Hole transport layer (20 nm): compound 10
[0110] Light-emitting layer (40 nm): exemplified compound 1-1
(concentration by weight: 10%); compound 11 (concentration by
weight: 90%)
[0111] Electron transport layer (30 nm): compound 12
[0112] Metal electrode layer 1 (0.5 nm): LiF
[0113] Metal electrode layer 2 (150 nm): Al
[0114] The structural formulae of compounds 10, 11, and 12 are
shown below.
##STR00027##
[0115] The characteristics of the resulting organic light-emitting
element were measured and evaluated. Specifically, the
current-voltage characteristics of the element were measured with
microammeter 4140B manufactured by Hewlett-Packard Company, and the
emission luminance of the element was measured with BM7
manufactured by Topcon Corporation. The organic light-emitting
element showed blue light emission of x=0.19 and y=0.34 in the CIE
standard color system at an emission luminance of 1000 cd/m.sup.2
and also showed a luminous efficiency of 18.4 cd/A and an external
quantum yield of 8.4%. Further, when a voltage was applied to the
element for 100 hours in a nitrogen atmosphere, good continuous
light emission was confirmed.
[0116] Therefore, an iridium complex according to the present
invention is a novel compound having high quantum yield and
emission suitable for blue color and capable of producing a
light-emitting element having good emission characteristics when
used for an organic light-emitting element.
[0117] As described above by giving the embodiments and the
examples, the present invention can provide an iridium complex
which is excellent in blue light emission characteristics. Also,
the invention can provide an organic light-emitting element having
excellent emission characteristics.
[0118] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
[0119] This application claims the benefit of Japanese Patent
Application No. 2009-278969, filed Dec. 8, 2009, which is hereby
incorporated by reference herein in its entirety.
* * * * *